The structure of natural somatostatin was first elucidated by Brazeau et al., Science, 179, 77 (1973) as the cyclic tetradecapeptide ##STR1## Somatostatin has been synthetically produced by the solution method (Sarantakis et al., Biochem. Biophys. Res. Comm., Vol. 54. No. 1, pp. 234-238 (1973) and Immer et al., Helv. Chem Acta, 57, No. 81, pp. 730-734 (1974) and the solid phase method (Rivier, J.A.C.S. 96, 9, pp. 2986-2992 (1974).